Zen Cart is a shopping cart based on the old oscommerce engine but it offers tons of more features and has an active support community. You can use this to sell items over the internet*. You can visit Zen Cart's website for more details and to see examples of it being used. http://www.zen-cart.com/ .
- You will still need to make arrangements for receiving and processing payments in a secure manner
Dreamhost Zenners check this thread so you can fix a serious customer login session bug that only seems to happen on Dreamhost: http://www.zen-cart.com/forum/showthread.php?t=37465
Dreamhost also has a problem with IP to Host Conversion. If you are experiencing painfully slow delays only on the initial load of your website (up to 30 seconds) then you need to disable this feature. Go the to Zen Cart Admin Panel, and click on Configuration-> Sessions, then set IP to Host Conversion Status to "False".